PROJECT SUMMARY/ABSTRACT Despite its effectiveness in the prevention of HIV transmission, uptake of pre-exposure prophylaxis (PrEP) among gay, bisexual, and other men who have sex with men (GBM) has been slow. Much of the research conducted aiming to increase uptake has focused on facilitators and barriers to beginning a PrEP regimen, however to what end these barriers are relevant to young GBM (YGBM), especially those under 18, is largely unknown. PrEP is not yet approved for those under 18, however because of their substantial risk and being the only age group for which rates of new HIV infections continues to increase, understanding their unique barriers to uptake is imperative so interventions aiming to increase uptake among this population are ready to be implemented once approved. Furthermore, research has shown that PrEP is being prescribed off label to some HIV at-risk YGBM. At this time there has not been enough research to understand the needs, concerns, barriers, and facilitators that YGBM face when considering and initiating a PrEP regimen. The primary goal of this F31 NRSA is to provide the relevant training to facilitate completion of a study to provide useful data that can be used to inform future interventions looking to increase uptake of PrEP among YGBM who are at substantial risk for HIV acquisition. As such, the research project has 3 aims: (1) examine prevalence of PrEP use and discontinuation in a diverse national sample of approximately 6,000 YGBM (16-24); (2) among approximately 2,400 YGBM, we will identify group differences in familiarity with, intentions to begin, and unique barriers to PrEP. With primary outcomes for this aim being PrEP familiarity, intentions, and unique barriers to uptake for YGBM, we will be able to report findings that can be used to inform future interventions aiming to increase uptake and inform the adaptation of the Motivational PrEP Cascade to meet the specific needs of YGBM; and (3) among the same sample, we will utilize the longitudinal data to examine their movement along the Motivational PrEP Cascade over the course of one year. Specifically, we will look at changes in candidacy for PrEP as defined by CDC criteria and uptake of PrEP; among those who initiate PrEP, we will also examine adherence and discontinuation. These findings will aid in making appropriate modifications to the PrEP Motivational Cascade so that it can be used for increasing PrEP uptake for YGBM. The proposed project will leverage as existing NIH-funded study (UG3-AI1336740; MPI: Parsons & Rendina) in a way that is feasible, low cost, and still high impact. This project has the potential to inform future intervention aiming to: 1) target specific demographics of at-risk YGBM for PrEP uptake, 2) increase uptake for YGBM by understanding their specific barriers to uptake, and 3) understand initiation, adherence, and discontinuation in the presence of sexual risk for this at-risk group. The research and training plan proposed in this project are also designed to foster my development as a researcher with a strong foundation in sexual risk, HIV prevention, preventative medicine, and sexual minority populations.